Study on the dynamic and static mechanical properties of microsphere rubber powder reinforced oil well cement composites

Using fillers to toughen and reduce the brittleness of oil well cement (OWC) is very important for prolonging the service life of oil and gas wells. However, most studies have focused on investigating the reinforced mechanical properties of OWCs under static loads, which cannot be applied in predicting the service life of oil and gas wells because OWCs are usually exposed to dynamic loads in practice. In this study, the reinforced mechanical properties of OWCs under both dynamic and static loads are investigated for the first time, and microsphere rubber powders (MRPs) are adopted to reinforce G-class oil well cement. The results show that optimal mechanical properties and a maximum energy absorption rate exist under both dynamic and static loads, and the sample with MPR has the maximum impact resistance. In addition, blank cement is more prone to fracture under dynamic loading than under static loading. Under the dynamic load impact condition, the energy absorbed by the sample with MRP is much higher than that of blank cement, and the toughness of the sample increases. Based on the results of these tests and micromorphological observations, the energy dissipation mechanism of microsphere rubber powder for toughening and brittleness reduction is explained from three aspects: the long-range strain dispersion effects under loading, microcrack initiation and propagation effects, and peeling and tearing effects at the interface.